The most common cause of tiredness is fever. Infectious diseases, abnormal liver or kidney function, anemia, hypokalemia, and in women, pregnancy may be the cause. The most common cause is fever, which may occur in patients with infectious diseases due to physical exertion and fever. It is recommended to check the blood test, C-reactive protein and other tests in the hospital to help clarify the initial condition. Patients with abnormal liver and kidney function also often have symptoms of generalized fatigue. It is recommended that you can go to the hospital for liver and kidney function, ultrasound and other tests to help clarify the condition. Anemia and hypokalemia may cause fatigue. The former causes insufficient supply of nutrients and oxygen to the limbs, and the latter may cause abnormal electrical activity of muscles, which may cause fatigue. In addition, during pregnancy, women may also experience a lack of energy and fatigue due to elevated estrogen and progesterone. In addition to the common causes mentioned above, it may also be caused by hypothyroidism and other diseases, or it may be caused by overwork or over-exercise, if it is not relieved after resting, it is recommended to consult a doctor.